The striker has been injured and out of favor under the new manager at Aston Villa this season but returned to the team to score against former club Ipswich in the FA Cup.
Bent had been sidelined with a hamstring injury in recent weeks and struggled to win a place in the Villans XI before that due to the good form of new signing Christian Benteke. The 28-year-old grabbed the equalizer after Michael Chopra had opened the scoring at Villa Park, though, and Andreas Weimann added a second to secure their safe passage into the fourth round.
"That finish is Darren Bent down to a tee," Lambert told reporters. "It was top class. His overall game was very good - his whole work ethic, the way he played. But his general game was very good."
Bent had not scored since Sept. 30, but has now bagged four goals in his last five appearances in the FA Cup.
Lambert will now have to decide whether to include Bent in his squad for the first leg of the club's League Cup semifinal against Bradford on Tuesday.
"Considering he only really trained with us yesterday, it was a big, big effort from him," Lambert said. "We left out a few lads to give them a break and I was delighted with everyone that came in. I thought it was a massive effort."